1. Field of the Invention
The invention concerns a machining center with a workpiece machining tool.
2. Description of the Related Art
The principle of workpiece machining tools such as, for example, tools for grinding, milling, turning etc. of workpieces has long been known. These serve on the one hand for the repair of work tools, that is, for example, for re-sharpening the cutting edges of cutting tools, wherein the cutting geometry should be re-established to the closest extent possible, and on the other hand for processing a raw form, that is, for example, for producing a turned part or for the milling-in of grooves, etc., and complicated milled parts, such as can only be produced using interpolated NC-axis.
This type of workpiece processing machine is generally constructed upon a machine stand, which includes the various construction components necessary for functioning. This includes, first, the working plate which is seated upon the machine stand and-oriented horizontally, which as a rule is dimensioned with high precision and is adapted to having further construction components secured thereto.
A workpiece carrier is seated upon the working plate, which receives the workpiece to be machined. The workpiece carrier is equipped for example with a longitudinal and a transverse support, which permit a rapid adjustment respectively in the longitudinal as well as in the transverse direction. Further, the workpiece spindle integrated in the workpiece carrier and receiving the workpiece is free or coupled with the longitudinal support and here drivable, such that any combination of rotational and advancing movements is achievable.
The machining of the workpiece occurs by means of a machining tool, for example by means of a grinding disk, a miller, a chisel, a drill, etc., which is provided interchangeably on a machining head. Depending upon need the machining head is adjustable along multiple axis, so that a desired contour can be followed. For this, the machining head is mounted on a vertically oriented and height adjustable machining column, wherein the machining column for its part is pivotable about a vertically oriented axis and is provided upon a rotary plate. The rotary plate as a rule is likewise seated upon a working plate. Therein it is positioned adjacent to the workpiece carrier in such a manner that the machining tool can be directed onto the workpiece.
From EP 0 700 751 B1, representative of the state of the art over which the present invention represents an improvement, it is known to seat the rotary disk with the thereupon secured machining column not upon the working plate, but rather to integrated it therebelow in the machine stand so that, in comparison to the arrangement wherein the rotary plate is seated upon the working plate, an unimpeded access to the working area is always possible.
According to EP 0 700 751 B1 the pivot movement of the machining head is made possible by securing the machining column carrying this onto a carrier arm, which at one end is attached to the rotary plate and at the other end extends sideways out from the machine stand in order to be able to receive the machining column.
In order to attempt to achieve a stability similar to the workpiece machining tools in which the rotary disk is seated upon the working plate, the rotary plate is double-mounted. In practice this is realized thereby, that a mounting bolt is provided, which extends centrally through the rotary plate and projects both above and below the rotary plate. Journals are provided at the respective projecting bolt ends, which are supported within the machine stand and/or below the working plate.
A mounting device for a light drill tool guided along an arc is described in U.S. Pat. No. 1,630,528. In order to make possible a wide accessibility to the work area, a frame holding the drill tool is provided, which tool is guided upon arcuate curved tracks provided above this frame via a wheel with a wheel flange, the wheel mounted rotatably, oriented vertically, and guided on the upper side of the frame. In order to prevent a pivoting of the frame mounted on the curved track in the direction radially or as the case may be tangential to the guide trackl, the lower end of the frame holding the drill tool is guided upon a track which is also arcuate shaped below the workpiece. For this purpose, the frame is shaped with a projection at the workpiece facing end. The projecting end of the frame includes rollers mounted rotatably in a vertically oriented axis, wherein respectively two rollers encompass the arc shaped rails, so that the total frame is guided in an arc.
Since the wheel with wheel flange provided on the upper side of the frame can essentially receive or accept only a (limited) force in the vertical direction and the rollers mounted at the lower end of the frame can tolerate or accept a limited force in the radial direction, the mounting device according to U.S. Pat. No. 1,630,528 is suitable only for a machining process in which the tool transmits only small forces upon the workpiece and/or processes with high dimensional tolerances.
Frequently however the stability of the guide arrangement according to U.S. Pat. No. 1,630,528 or even the doubled mounting according to EP 0 700 751 B1 is still not sufficient, particularly not when the machining column is made more stable and/or supplemental construction components such as motors for raising or tilt adjusting of the machining head are incorporated, or when, for example in a milling process, a greater force must be transmitted to the workpiece being machined.
The invention is thus concerned with the task of developing a workpiece machining tool of the type described in the introduction in such a manner that it is no longer liable to the above-mentioned disadvantages. In particular, a machining center of this type with a workpiece machine tool is to be provided, with which the mounting for the pivotable machining column is to be made even more stable, without losing the compact construction and the unimpeded access to the work area, so that a universal employment is possible.
This problem is solved for a machining center of this type by means of the features indicated in the characterizing portion of claim 1.
Advantageous embodiments and further developments of the invention can be seen from the dependent claims.
The invention is based upon the idea of stably mounting not only the rotating plate, but rather, to provide a further mounting position, which is provided supplementally to the already present journal or bearing, in axial extension on the opposite side of the machining head. In concrete terms, a mounting device is provided which includes a mounting position above the machining head in the axial extended axis of the rotating plate, at which a second carrier arm connected to the machining column is mounted for the machining column. Accordingly, also in this inventive arrangement, the machining column is provided outside of the working plate, whereby the working area is optimally accessible, that is, unimpeded from all sides. Further, by this type of mounting, the ability of the rotary plate to accept loads is substantially increased in comparison to the conventional one-sided double mount.
Thereby the precision of the workpieces being processed can be significantly increased, in particular also in the case that an elevated application pressure is necessary. Further, the machining column can be made more stable and/or serve for mounting supplemental components such as motors for raising and lowering adjustment of the machine head.
In accordance with the present invention, the motor drive of the pivot arm is preferably associated with the first (lower) carrier arm, so that the mounting position of the upper carrier arm is displaceable in the vertical direction. Thereby tolerances which are unavoidable during assembly can be compensated for.
In a particularly preferred embodiment of the invention the mounting device is in the form of a machine frame. This machine frame is preferably so designed, that it essentially encompasses the machine stand, the working plate, the workpiece carrier, the machining tool, the machining head, the machining column, and the rotary plate as well as the first and second carrier arms. Besides the simplified integration of the second mounting point above the machining head along the axial extension of the axis of the rotary plate, such a compact form further exhibits the advantage, that the machining center or as the case may be a separate unit can be transported to the set-up location, without having to provide additional protective devices for the individual machine components. Further, no dirtying of the machine occurs from outside by other machines positioned adjacent thereto, or on the other hand, the particles or shavings produced by processing of the workpiece in the machine itself cannot escape to the outside.
It is further envisioned that the machine frame is comprised of mineral cast components. A particularly advantageous embodiment of the invention envisions that the mineral cast components of the frame are adhered to each other and/or screwed together. The advantage of this embodiment lies in the attainability of an optimal stiffness.
According to a particular preferred embodiment of the invention, the machine framework includes a dismantleable covering with a sliding door. The sliding door makes possible an optimal accessibility to the working area during the working process itself; the easily disassembled covering makes possible the accessibility from the side to the components of the machine for repair and/or service purposes.
An inventive alternative to the above described machine frame is comprised therein, that the framework is in the form of a bridge, which essentially passes over the machine stand, the working plate, the workpiece carrier, the machining tool, the machining head, the machining column, the rotary plate and the first and second carrier arms. Here also it is guaranteed that the second mounting point is integrated in simple mode and manner above the machining head in the axial extension of the axis of the rotary plate. The machining center constructed in this mode and manner further exhibits the advantage that the individual components are on the one hand very simple to produce and on the other hand that the transportation and assembly can be carried out in simple manner.
In accordance with a particularly advantageous variant of this embodiment, a cable channel is provided in the bridge, in which supply lines or the like for this machine, or machines provided in close proximity to this machining center, can be received. Since it is frequently the case that the supply lines for this type of machine or as the case may machining center must be carried by special carrier or retaining devices, it becomes possible in this case to dispense with a separate device.
In accordance with a further modification of this variant, a housing part is rotatably mounted upon the bridge, which at least partially encompasses the working plate, the workpiece carrier, the machining tool, the machining head, the machining column, the rotary plate and the first and second carrier arms. This housing part functionally corresponds essentially to the sliding door of the above-mentioned variant. It makes possible on the one hand an optimal accessibility of the operating area during the working process itself. It is however, beyond this, made possible, that the working plate, the workpiece carrier, the machining tool, the machining head, the machining column, the rotary plate and the first and second carrier arm are protected from unauthorized access.
Preferably, this rotatably mounted housing part is in the form of a segment of a cylindrical casing, wherein the casing surfaces are essentially oriented vertically. A housing part of this kind is easy to manufacture and is particularly suited to being rotated at least partially into a fixed housing part. This fixed housing part can likewise be in the form a section of a cylindrical casing.
For manufacturing reasons, it is advantageous to produce the bridge of steel. Besides this, a steel bridge ensures high stability of the total device, so that a very precise processing of the work is made possible.
In accordance with the invention it is further envisioned, that the fixed housing part is made of sheet metal and the rotatable mounted housing part is made of MAKROLON (polycarbonate, product of Bayer), glass (fiberglass) or the like. A sheet metal cover has in general the advantage of the low cost of manufacturability, the transparent version of the rotatably mounted housing part enables optical monitoring of the parts which are accessible during processing.
For cost and stability reasons the rotatably mounted housing part is preferably provided with a steel lid.